Imagine you want a toy that costs $100, but you don't have all the money now. The toy store tells you they can give you a 0% finance option to buy the toy. This means they will let you take the toy home now, and you can pay for it over some time, maybe 6 months or a year.
But wait, if you are paying over time, won't they charge you interest? That's what happens when you borrow money, right? Well, in this case, they won't charge you any interest. This means you will still only have to pay back the $100 you borrowed for the toy, not more.
It's like borrowing money from a very nice friend who doesn't want to make money off you. So, you get to have your toy now and pay for it later with no extra fee. But remember, borrowing money is still a serious thing, so make sure you can pay it back on time!